transponder

noun

tran·​spon·​der tran(t)-ˈspän-dər 

: a radio or radar set that upon receiving a designated signal emits a radio signal of its own and that is used especially for the detection, identification, and location of objects and in satellites for relaying communications signals

Did you know?

This word was coined during World War II by simply joining pieces of the words transmitter and responder. Transponders are basic to modern aviation and communications satellites, and they're finding new uses in fields such as medicine as well. But they're now also part of everyday life. The "E-ZPass" that lets you drive right through turnpike tollbooths is a transponder, and the car you're driving may not even start unless it recognizes the signal from your personal key's transponder. In a big crowded foot race, you may carry a tiny transponder on your shoe that records when you cross both the starting line and the finish line.

Examples of transponder in a Sentence

Recent Examples on the Web

Fortunately in the other two cases, the damage had not knocked out their transponders, so communication to diagnose and fix the resulting problems was still possible. —Keith Cooper, Space.com, 13 Feb. 2025

The plane’s radio transponder stopped transmitting about 2,400 feet short of the runway, roughly over the middle of the river. —Lolita C. Baldor, TIME, 30 Jan. 2025

Meanwhile, the plane’s radio transponder stopped transmitting over the middle of the Potomac River and around 2,400 feet short of the runway. —Charna Flam, People.com, 30 Jan. 2025

The plane’s transponder stopped transmitting about 2,400 feet (732 meters) short of the runway, roughly over the middle of the river. —Sarah Brumfield, Chicago Tribune, 30 Jan. 2025

Word History

Etymology

transmitter + responder

First Known Use

circa 1944, in the meaning defined above

Rhymes for transponder

• responder
• condor
• fonder
• launder
• mandir
• maunder
• ponder
• squander
• wander
• yonder